This invention relates generally to damping and controlling vibration of rotors, and more particularly concerns such damping and controlling of vibration of rotors which carry rotating rings of liquid.
The dynamic stability of rotors partially filled with viscous incompressible fluids is critical to successful operation of many types of devices employing such rotors. Examples are centrifuges, liquid cooled machinery, spinning ordnance projectiles and two-phase turbines, there being many others. Theoretical studies in which the equations characterizing rotor dynamics are coupled with equations of motion for rotating fluids have identified specific regimes of stable and unstable motion. Among important factors are angular frequency, rotor and housing stiffness and damping, and fluid properties. Unstable modes are caused by waves in the liquid which, if not damped or suppressed, can result in catastrophic failure of the machine. This phenomena has been encountered in rotary separators and turbines of the type described herein, and characterized by a rotating ring of liquid. Flow field observations have identified a liquid wave tending to surge and rotate relative to the liquid channel at frequencies typically in the range 85% to 95% of rotor speed.